1. Technical Field
The present invention relates to an illumination device and a projector.
2. Related Art
In the past, there has been known a projector, which modulates light emitted from an illumination device to thereby form an image corresponding to image information, and projects the image on a projection target surface such as a screen in an enlarged manner. As such a projector, there is known a projector provided with a light source device having a solid-state light source and a fluorescence emitting plate (see, e.g., JP-A-2012-137744 (Document 1)).
In the projector described in Document 1, the light source device is provided with a solid-state light source unit, two wave plates, a dichroic mirror, a fluorescence emitting plate, and a reflecting plate. Among these constituents, the solid-state light source unit emits excitation light as blue light, and one of the wave plates makes first polarization component and a second polarization component generated by converting the polarization direction of the excitation light enter the dichroic mirror. The dichroic mirror performs polarization separation on the first polarization component and the second polarization component. The fluorescence emitting plate emits fluorescence including components of green and red due to the excitation light of the first polarization component. The other of the wave plate converts the excitation light of the second polarization component into the circularly-polarized excitation light, and the reflecting plate reflects the excitation light having been transmitted through the wave plate, and makes the reflected light enter the wave plate again.
Then, the dichroic mirror described above transmits the fluorescence irrespective of the polarization direction. Therefore, the fluorescence generated in the fluorescence emitting plate is transmitted through the dichroic mirror, and the excitation light having been reflected by the reflecting plate and then transmitted through the other of the wave plates described above is reflected by the dichroic mirror toward the same direction as the proceeding direction of the fluorescence. Thus, white illumination light formed of the excitation light as the blue light and the fluorescence including the green light and the red light is emitted from the light source device.
Incidentally, in the light source device described in Document 1 mentioned above, in the configuration of separating the excitation light used as the blue light using the dichroic mirror, and combining the excitation light with the fluorescence generated by the fluorescence emitting plate, the reflecting plate and the wave plate for reflecting the excitation light become necessary. There is a problem that such a light source device is difficult to miniaturize.
In contrast, it is possible to adopt a configuration of making roughly the whole of the excitation light having been emitted from the solid-state light source unit enter the fluorescence emitting plate, converting a part of the excitation light into fluorescence, and using an unconverted part of the excitation light as the blue light.
However, in such a configuration, there is a problem that it is difficult to control the color tone of the illumination light emitted from the light source device.